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<head>
  <meta charset="UTF-8">
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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>
  <script>
    var arr = [2, 13, 1, 5, 4]

    // console.log( arr.reverse() )  // 反转数组

    // console.log( arr.sort() )  // 排序数组

    console.log( arr.sort(function(a, b) {
      return a - b
    }) )
    
    console.log( arr.sort(function(a, b) {
      return b - a
    }) )
  </script>
</body>
</html>